Group portrait of the VLT with laser beam

Night view on Cerro Paranal, home to ESO’s Very Large Telescope (VLT), the world’s most advanced observatory. 

Among the circular trails imprinted by the stars in a dark and clear night, a laser beam shoots out of one of the Unit Telescopes of the VLT. This beam is used to create an artificial star above Paranal to assist the adaptive optics instruments on the VLT. 

Adaptive optics is a technique that allows astronomers to overcome the blurring effect of the atmosphere and obtain images almost as sharp as would be possible if the whole telescope were placed in space, above Earth's atmosphere.